<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <script src="angular.js"></script>
    <title>练习</title>
</head>
<body ng-app="">
    Your name : <input type="text" ng-model="khj" placeholder="World">
    <hr>
    Hello {{yourname || 'World'}}!
</body>
</html>